ARM: 8175/1: Use current_stack_pointer to calculate pt_regs address

Use the global current_stack_pointer to calculate the end of the stack for
current_pt_regs()

Signed-off-by: Behan Webster <behanw@converseincode.com>
Reviewed-by: Mark Charlebois <charlebm@gmail.com>
Reviewed-by: Jan-Simon Möller <dl9pf@gmx.de>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/ptrace.h

@@ -154,9 +154,8 @@ static inline unsigned long user_stack_pointer(struct pt_regs *regs)
 	return regs->ARM_sp;
 }
 
-#define current_pt_regs(void) ({				\
-	register unsigned long sp asm ("sp");			\
-	(struct pt_regs *)((sp | (THREAD_SIZE - 1)) - 7) - 1;	\
+#define current_pt_regs(void) ({ (struct pt_regs *)			\
+		((current_stack_pointer | (THREAD_SIZE - 1)) - 7) - 1;	\
 })
 
 #endif /* __ASSEMBLY__ */